Preheat oven to 375 F. In a stainless steel skillet over medium high heat, melt 10 tbsp butter and cook 3-5 minutes, until dark golden brown with a nutty aroma, swirling constantly so it doesn't burn.
Transfer to a heatproof bowl and stir in the remaining 4 tbsp butter (room temperature) until it's melted.
Whisk the sugars, salt and vanilla into the butter for 30 seconds. Add egg and egg yolk and mix until smooth.
Let mixture stand for a minute, then whisk for 30 seconds. Repeat 2 times until the mixture is thick and shiny.
With a rubber spatula, mix in the flour, baking soda, and cinnamon until just combined. Stir in chocolate chips and walnuts.
Scoop 2 tbsp dough onto cookie sheet about 2 inches apart. Bake for 8-12 minutes, until edges are crispy but inside is still soft. Let rest for 5 minutes before transferring to a wire cooling rack to cool completely.